Out of 100 children, the total number of children who do not play
(i) football = 100 – 65 = 35
(ii) volleyball = 100 – 70 = 30
(iii) basketball = 100 – 75 = 25
So, the maximum number of children who do not play at least one game is
35 + 30 + 25 = 90
Thus, the minimum number of children who play all three games is
100 - 90 = 10
Hence, the smallest percentage of children playing all three games is 10%.
Note: The greatest percentage of children playing all three games = min(65%, 70%, 75%) = 65%.